On Thu, Nov 24, 2016 at 10:25:11AM +0000, Mark Rutland wrote:

For several reasons, it would be beneficial to kill off ACCESS_ONCE()
tree-wide, in favour of {READ,WRITE}_ONCE(). These work with aggregate types,
more obviously document their intended behaviour, and are necessary for tools
like KTSAN to work correctly (as otherwise reads and writes cannot be
instrumented separately).

While it's possible to script the bulk of this tree-wide conversion, some cases
such as the virtio code, require some manual intervention. This series moves
the virtio and vringh code over to {READ,WRITE}_ONCE(), in the process fixing a
bug in the virtio headers.

Thanks,
Mark.

I don't have a problem with this specific patchset.

Though I really question the whole _ONCE APIs esp with
aggregate types - these seem to generate a memcpy and
an 8-byte read/writes sometimes, and I'm pretty sure this simply
can't be read/written at once on all architectures.

So I worry it's kind of like volatile in this respect,
too easy to overuse.

Mark Rutland (3):
  tools/virtio: fix READ_ONCE()
  vringh: kill off ACCESS_ONCE()
  tools/virtio: use {READ,WRITE}_ONCE() in uaccess.h

 drivers/vhost/vringh.c        | 5 +++--
 tools/virtio/linux/compiler.h | 2 +-
 tools/virtio/linux/uaccess.h  | 9 +++++----
 3 files changed, 9 insertions(+), 7 deletions(-)

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2.7.4